Hardening printed ink films



y 3, 1951 A. F. SCHMU'TZLER 2,558,787

HARDENING PRINTED INK FILMS Filed April 4, 1945 INVENTOR ALFRED F.-SCIY-IMIJTZLEA BY FLWw' ATTORNEYS aiented July 3, 1951 UNITED STATESPATENT OFFICE HARDENING PRINTED INK FILMS Alfred F. Schmutzler, Teaneck,N. J.

Application April 4, 1945, Serial No. 586,548

1 Claim. 1

This invention relates to the drying of steamsetting printing inks.

Steam-setting printing inks usually comprise a coloring materialhomogeneously suspended in a lacquer-like composition, in which thesolvent is a liquid polyhydric alcohol. They may be used on the usualcommercial printing presses, and their printed films can be dried byexposure to steam.

The hardening or drying of these ink films is a precipitationphenomenon. The steam, usually issuing from a row of jets, saturates theatmosphere with moisture, While the water soluble solvent absorbssufficient water to cause the separation of the binder. During thisprecipitation, the coloring material adheres to the binder. In thisprocess of hardening printing ink films, the drying proceeds in onedirection, e. g. from the outer layer toward the paper.

This steam-setting method was developed due to the disadvantagesencountered with a somewhat older quick drying process relying upon thedirect heat from gas burners. The latter treatment dries out the paperand usually causes it to shrink. The steam treatment eliminates thisdefect; it has met with great success in printing processes other thanthat with high speed rotary presses as of the type shown in Gessler U.S. Patent 2,317,372 of April 27, 1943. Apparently the shorter exposureof the printed ink films on the speeding web is not sufiicient to drythe ink. Longer exposures to steam by multiplying the number of rows ofsteam jets is not always effec tive. Especially at low atmospherichumidity, it seems that a layer, impermeable to steam, surrounds thespeeding web; and in such a layer the humidity is not substantiallyraised to cause the hardening of the printed ink films.

I have found that by raising the moisture content of the paper prior toprinting, the printed films from steam-setting printing inks harden morequickly during subsequent exposure to heat or steam. This procedure willfacilitate the drying of steam-setting printing ink films on rotary highspeed presses.

The paper or the web may be moistened by a fine spray of Water, such asfrom an atomizer, or a jet of steam, or the moistening of the paper maybe accomplished by a system of printing press rollers. Since paper hasthe capacity to hold widely varying percentages of water, control ofwetting is necessary but not critical; relatively large proportions ofwater above the normal moisture content of paper may be applied withoutefiecting proper printing operations.

If the paper is moistened by a system of printing press rollers duringthe operation of a high speed rotary printing press, the water haslittle chance to penetrate deeply into the web before the printing takesplace. Thus the moisture will be at the outermost layer where it isneeded for its task Furthermore, if the paper is exposed to the directheat of impinging flames, its tendency to shrink is considerablyreduced. Whether the final hardening of the printed film will beaccomplished by direct heat or by the exposure to steam, either methodcombined with moistening the paper prior to printing effects thehardening of the ink film from both sides.

The application of this invention may be illustrated by the followingexamples:

Example I Figure 1 schematically presents the path of a web of fibrousmaterial through the printing process on a rotary press. As the web offibrous material unwinds from roller E, its surface is wetted by themoistening roller D, which may also serve as the tension roller. Thewater supplied comes from the fountain A, in which roller B isthoroughly wetted; distributing roller C is wetted by roller B, and ittransfers the water to the moistening roller D. It is understood thatthe set of rollers require an elaborate arrangement for adjusting therollers; they may be adjusted so that they do not touch each other ormay be adjusted so that they would squeeze each other. Any intermediateadjustment controls the amount of Water transferred to the surface ofthe web on its path tothe printing mechanism. Though the hardening ofthe printed ink film is independent of the printing mechanism, Figure 1illustrates a usual arrangement, such as an ink fountain F, from whichthe ink is picked up by roller G; distributing roller H shears the inkofi roller G, and transfers it to the impression roller I, which inksthe web while it is passing over the roller K. After printing, themoisture in the surface of the paper aids the impinging steam, issuingfrom the orifices of a row of steam pipes L, in hardening the printedink films.

Since sufficient moisture is already available in the surface of thefibrous material, steam is really not necessary to cause the hardeningof steamsetting printing inks; some other form of heat, such as from anelectric heating element, or from gas burners or oil burners, will justas well accomplish the hardening of the ink film.

After the ink film ls hardened, it is customary Example II In order tomoisten the web of fibrous material shortly before printing, rows ofsteam jets may be placed around the unwinding roller E and along thepath of the web ahead of the printing mechanism, as illustrated inFigure 2, which indicates the usual path of the web of fibrous materialon a rotary printing press, as explained in Example 1. Steam pipes withtiny orifices are arranged in rows A, B, C and D so that the orificesface the web. As the roller E unwinds and the web travels toward theprinting mechanism, all or part of the steam pipes can be brought intooperation to wet the surface of the fibrous material for proper printingoperation. The number of pipes in operation will depend upon the speedof the press and the pressure of the steam. After the printing, themoisture in the surface of the paper aids the impinging steam, issuingfrom the orifices of a row of steam pipes L, in hardening the printedink films.

In place of steam pipes for moistening the web of fibrous material priorto printing, water pipes with atomizers can be installed.

Example III The unwinding web is cooled below room temperature by eitherexposing it to liquid air, solid carbon dioxide (Dry Ice) or by passingit over several supercooled rollers, then a spray of steam or a spray ofatomized hot water is impinged upon the paper in order to moisten andreheat the paper, as closely to room temperature as desired, prior toprinting. After printing one of the several methods of drying may beapplied.

It is understood that the afore-mentioned examples are to serve as aguide and thatchanges may be made without departing from the scope 4 ofthis invention, as described and defined in the appended claim.

What is claimed is:

A method of improving the speed of hardening of a printed watersensitive ink film printed by a high speed rotary press on a rapidlymoving web of fibrous material, which comprises moistening the surfaceof said fibrous material immediately prior to printing with inkcomprising a coloring material, a water insoluble binder and a watermiscible solvent, forthwith printing said web while a substantialportion of the moisture is at said surface, and immediately afterprinting, causing the evaporation of excess moisture at the surface ofthe unprinted portion of the web to make it available for the thoroughhardening of said ink film.

ALFRED F. SCHMUTZLER.

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